There's a number of traders in China who sell Shuguang tubes, most of them have a minimum order value around 2k USD.

Pay a 25 USD one time charge + 0.2 USD/tube and have your own logo on then.

The premium you pay on TADs is for pretty boxes, retesting and so on.

I bought a batch of ca 120 tubes in bulk over a year ago, (a group buy), various types. One rectifier tube was DOA, no failures so far.
Pretty wide spread in parameters but within bias adjustment range as i didn't buy factory matched.

Their EL84 was a nice surpise as it takes over 400V plate voltage without any problems

In afterthought: my comment on "pretty boxes" may be taken as a negative opinion which it wasn't meant to be.

Adding all costs like shipping, testing, stocking, customer service i.e. warranty etc and a reasonable mark-up and bearing in mind that TAD & others are businesses and not "for fun but not for profit" outfits one has to conclude that 35 USD for a pair of matched 6L6 is a fair price.